Terminal device, base station device, communication method, and integrated circuit for decoding a physical downlink shared channel in a non-mbsfn subframe

ABSTRACT

A terminal device includes means of determining resource elements to which a physical downlink shared channel is mapped for transmission on the physical downlink shared channel in a non-MBSFN subframe that is scheduled by using a downlink control information format 1A based on positions of cell-specific reference signals that are provided by using a physical layer cell identity.

TECHNICAL FIELD

The present invention relates to a terminal device, a base stationdevice, a communication method, and an integrated circuit.

BACKGROUND ART

In radio communication systems such as Long Term Evolution (LTE) andLTE-Advanced (LTE-A) by Third Generation Partnership Project (3GPP) andWorldwide Interoperability for Microwave Access (WiMAX) by the Instituteof Electrical and Electronics Engineers (IEEE), each of base stationdevices and terminal devices includes single or plural transmit-receiveantenna, and a multiple-input multiple-output (MIMO) technology is used,thereby enabling realization of high speed data transmission.

Here, a discussion has been held about support for multiple-user MIMO(MU-MIMO) in which plural terminal devices perform spatial multiplexingby using same frequency and time resources in radio communicationsystems. Further, a discussion has been held about support for acooperative multipoint (CoMP) transmission scheme in which plural basestation devices cooperatively perform interference coordination. Forexample, a discussion has been held about a radio communication systemin heterogeneous network deployment (HetNet) with a macro base stationthat has wide coverage, a remote radio head (RRH) that has narrowercoverage than the macro base station, or the like.

A suggestion has been made that in such a radio communication system,for example, the base station device and the terminal device transmitand receive downlink data by a physical downlink shared channel (PDSCH)based on resource elements to which cell-specific reference signals aremapped (NPL 1).

CITATION LIST Non Patent Literature

-   NPL 1: PDSCH mapping issues in CoMP; 3GPP TSG RAN WG1 meeting #69    R1-122603, May 21th-25th, 2012.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

However, there is no description about specific procedures in a casewhere the base station device and the terminal device transmit andreceive the downlink data based on resource elements to which a physicalsignal or a physical channel is mapped in the above-described radiocommunication system.

The present invention has been made in consideration of the aboveproblem, and an object thereof is to provide a terminal device, a basestation device, a communication method, and an integrated circuit thatallow a base station device and a terminal device to transmit andreceive downlink data based on resource elements to which a physicalsignal or a physical channel is mapped and to perform efficientcommunication.

Means for Solving the Problems

(1) To achieve the above object, measures described below are employedin the present invention. That is, a terminal device in the presentinvention is a terminal device that communicates with a base stationdevice, the terminal device including: means of determining resourceelements to which a physical downlink shared channel is mapped fortransmission on the physical downlink shared channel in a non-MBSFNsubframe that is scheduled by using a downlink control informationformat 1A based on positions of cell-specific reference signals that areprovided by using a physical layer cell identity; and means ofdetermining resource elements to which the physical downlink sharedchannel is mapped for transmission on the physical downlink sharedchannel in the non-MB SFN subframe that is scheduled by using a downlinkcontrol information format that is different from the downlink controlinformation format 1A based on positions of cell-specific referencesignals that are indicated by using control information that is includedin the downlink control information format, in which the controlinformation is used to indicate one value among four values that areassociated with the positions of the cell-specific reference signals,and the four values that are associated with the positions of thecell-specific reference signals are configured by using higher layersignaling.

(2) Further, a base station device in the present invention is a basestation device that communicates with a terminal device, the basestation device including: means of determining resource elements towhich a physical downlink shared channel is mapped for transmission onthe physical downlink shared channel in a non-MBSFN subframe that isscheduled by using a downlink control information format 1A based onpositions of cell-specific reference signals that are provided by usinga physical layer cell identity; and means of determining resourceelements to which the physical downlink shared channel is mapped fortransmission on the physical downlink shared channel in the non-MBSFNsubframe that is scheduled by using a downlink control informationformat that is different from the downlink control information format 1Abased on positions of cell-specific reference signals that are indicatedby using control information that is included in the downlink controlinformation format, in which the control information is used to indicateone value among four values that are associated with the positions ofthe cell-specific reference signals, and the four values that areassociated with the positions of the cell-specific reference signals areconfigured by using higher layer signaling.

(3) Further, a communication method in the present invention is acommunication method of a terminal device that communicates with a basestation device, the communication method including: determining resourceelements to which a physical downlink shared channel is mapped fortransmission on the physical downlink shared channel in a non-MBSFNsubframe that is scheduled by using a downlink control informationformat 1A based on positions of cell-specific reference signals that areprovided by using a physical layer cell identity; and determiningresource elements to which the physical downlink shared channel ismapped for transmission on the physical downlink shared channel in thenon-MBSFN subframe that is scheduled by using a downlink controlinformation format that is different from the downlink controlinformation format 1A based on positions of cell-specific referencesignals that are indicated by using control information that is includedin the downlink control information format, in which the controlinformation is used to indicate one value among four values that areassociated with the positions of the cell-specific reference signals,and the four values that are associated with the positions of thecell-specific reference signals are configured by using higher layersignaling.

(4) Further, a communication method in the present invention is acommunication method of a base station device that communicates with aterminal device, the communication method including: determiningresource elements to which a physical downlink shared channel is mappedfor transmission on the physical downlink shared channel in a non-MBSFNsubframe that is scheduled by using a downlink control informationformat 1A based on positions of cell-specific reference signals that areprovided by using a physical layer cell identity; and determiningresource elements to which the physical downlink shared channel ismapped for transmission on the physical downlink shared channel in thenon-MBSFN subframe that is scheduled by using a downlink controlinformation format that is different from the downlink controlinformation format 1A based on positions of cell-specific referencesignals that are indicated by using control information that is includedin the downlink control information format, in which the controlinformation is used to indicate one value among four values that areassociated with the positions of the cell-specific reference signals,and the four values that are associated with the positions of thecell-specific reference signals are configured by using higher layersignaling.

(5) Further, an integrated circuit in the present invention is anintegrated circuit that is installed in a terminal device thatcommunicates with a base station device, in which the integrated circuitcauses the terminal device to provide: a function of determiningresource elements to which a physical downlink shared channel is mappedfor transmission on the physical downlink shared channel in a non-MBSFNsubframe that is scheduled by using a downlink control informationformat 1A based on positions of cell-specific reference signals that areprovided by using a physical layer cell identity; and a function ofdetermining resource elements to which the physical downlink sharedchannel is mapped for transmission on the physical downlink sharedchannel in the non-MBSFN subframe that is scheduled by using a downlinkcontrol information format that is different from the downlink controlinformation format 1A based on positions of cell-specific referencesignals that are indicated by using control information that is includedin the downlink control information format, and in which the controlinformation is used to indicate one value among four values that areassociated with the positions of the cell-specific reference signals,and the four values that are associated with the positions of thecell-specific reference signals are configured by using higher layersignaling.

(6) Further, an integrated circuit in the present invention is anintegrated circuit that is installed in a base station device thatcommunicates with a terminal device, in which the integrated circuitcauses the base station device to provide: a function of determiningresource elements to which a physical downlink shared channel is mappedfor transmission on the physical downlink shared channel in a non-MBSFNsubframe that is scheduled by using a downlink control informationformat 1A based on positions of cell-specific reference signals that areprovided by using a physical layer cell identity; and a function ofdetermining resource elements to which the physical downlink sharedchannel is mapped for transmission on the physical downlink sharedchannel in the non-MBSFN subframe that is scheduled by using a downlinkcontrol information format that is different from the downlink controlinformation format 1A based on positions of cell-specific referencesignals that are indicated by using control information that is includedin the downlink control information format, and in which the controlinformation is used to indicate one value among four values that areassociated with the positions of the cell-specific reference signals,and the four values that are associated with the positions of thecell-specific reference signals are configured by using higher layersignaling.

Effects of the Invention

The present invention allows a base station device and a mobile stationdevice to transmit and receive downlink data based on resource elementsto which a physical signal or a physical channel is mapped and toperform efficient communication.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic block diagram that illustrates a configuration ofa base station device according to this embodiment.

FIG. 2 is a schematic block diagram that illustrates a configuration ofa terminal device according to this embodiment.

FIG. 3 is a schematic diagram that illustrates an example of a radiocommunication system according to this embodiment.

FIG. 4 is a diagram that illustrates an example of mapping of physicaldownlink channels.

FIG. 5 is a diagram that illustrates an example of mapping of a physicaldownlink shared channel and downlink reference signals.

FIG. 6 is another diagram that illustrates an example of mapping of thephysical downlink shared channel and the downlink reference signals.

FIG. 7 is still another diagram that illustrates an example of mappingof the physical downlink shared channel and the downlink referencesignals.

FIG. 8 is yet another diagram that illustrates an example of mapping ofthe physical downlink shared channel and the downlink reference signals.

FIG. 9 is a diagram that illustrates an example of a processing flowaccording to this embodiment.

FIG. 10 is another diagram that illustrates an example of a processingflow according to this embodiment.

MODE FOR CARRYING OUT THE INVENTION

An embodiment of the present invention will hereinafter be described. Aradio communication system in the embodiment of the present inventionincludes a primary base station (also referred to as macro base station,first base station, first communication device, serving base station,anchor base station, or primary cell) and a secondary base station (alsoreferred to as RRH, pico base station, femto base station, Home eNodeB,second base station device, second communication device, cooperativebase station group, cooperative base station set, cooperative basestation, or secondary cell) as a base station device (also referred toas base station, transmitting device, cell, serving cell, transmittingstation, transmitting point, transmit antenna group, transmit antennaport group, or eNodeB). Further, the radio communication system includesa mobile station device (also referred to as terminal, terminal device,mobile terminal, receiving device, receiving point, receiving terminal,third communication device, receive antenna group, receive antenna portgroup, or user equipment (UE)).

Here, for example, heterogeneous network deployment may be applied tothe primary base station and the secondary base station, a unit or wholeof coverage of the secondary base station may be included in coverage ofthe primary base station. Further, the secondary base station may beplural secondary base stations.

FIG. 1 is a schematic block diagram that illustrates a configuration ofthe base station device according to this embodiment. Here, a basestation device 100 illustrated in FIG. 1 includes the primary basestation and the secondary base station. The base station device 100 isconfigured to include a data control unit 101, a transmit datamodulation unit 102, a radio unit 103, a scheduling unit 104, a channelestimation unit 105, a receive data demodulation unit 106, a dataextraction unit 107, a higher layer 108, and an antenna 109. Further, areceiving unit is configured with the radio unit 103, the schedulingunit 104, the channel estimation unit 105, the receive data demodulationunit 106, the data extraction unit 107, the higher layer 108, and theantenna 109. Further, a transmitting unit is configured with the datacontrol unit 101, the transmit data modulation unit 102, the radio unit103, the scheduling unit 104, the higher layer 108, and the antenna 109.Here, the units that configure the base station device 100 may also bereferred to as units.

The data control unit 101 receives transport channels from thescheduling unit 104. The data control unit 101 maps signals generated bythe transport channels and physical layers on physical channels based onscheduling information that is input from the scheduling unit 104.Mapped data are output to the transmit data modulation unit 102.

Further, the data control unit 101 maps a PDSCH to a resource elementbased on a resource element to which a physical signal or physicalchannel is mapped. For example, the data control unit 101 performsrate-matching based on a position of a cell-specific reference signalthat is determined in accordance with a physical layer cell identity.Further, the data control unit 101 performs rate-matching based on theposition of the cell-specific reference signal that is specified for theterminal.

The transmit data modulation unit 102 modulates and codes transmit data.The transmit data modulation unit 102 performs signal processing such asmodulation and coding, serial-parallel conversion of input signals, anInverse Fast Fourier Transform (IFFT) process, and cyclic prefix (CP)insertion with respect to the data input from the data control unit 101based on the scheduling information or the like from the scheduling unit104, generates the transmit data, and output the transmit data to theradio unit 103.

The radio unit 103 performs up-conversion of the transmit data inputfrom the transmit data modulation unit 102 into radio frequencies togenerate radio signals and transmits the radio signals to the terminalvia the antenna 109. Further, the radio unit 103 receives the radiosignals that are received from the terminal via the antenna 109,performs down-conversion of the radio signals into baseband signals, andoutputs the receive data to the channel estimation unit 105 and thereceive data demodulation unit 106.

The scheduling unit 104 performs mapping of logical channels and thetransport channels, scheduling for a downlink and an uplink, and soforth. The scheduling unit 104 integrally controls process units of thephysical layers. Thus, interfaces are present between the schedulingunit 104 and the antenna 109, the radio unit 103, the channel estimationunit 105, the receive data demodulation unit 106, the data control unit101, the transmit data modulation unit 102, and the data extraction unit107.

Further, in the scheduling for the downlink, the scheduling unit 104performs transmission control of the transport channels and the physicalchannels and generation of scheduling information based on uplinkcontrol information that is received from the terminal, schedulinginformation that is input from the higher layer 108, and so forth. Thescheduling information that is used for the scheduling for the downlinkis output to the data control unit 101.

Further, in the scheduling for the uplink, the scheduling unit 104performs generation of scheduling information based on uplink channelstates that are output by the channel estimation unit 105, schedulinginformation that is input from the higher layer 108, and so forth. Thescheduling information that is used for the scheduling for the uplink isoutput to the data control unit 101.

Further, the scheduling unit 104 maps downlink logical channels that areinput from the higher layer 108 on the transport channels and outputsthe downlink logical channels to the data control unit 101. Further, thescheduling unit 104 processes uplink transport channels and control datathat are input from the data extraction unit 107 as necessary,thereafter maps the uplink transport channels and the control data onuplink logical channels, and output those to the higher layer 108.

In order to demodulate signals that are transmitted by the uplink, thechannel estimation unit 105 estimates the uplink channel states fromuplink reference signals (for example, demodulation reference signals)and outputs the uplink channel states to the receive data demodulationunit 106. Further, in order to perform the scheduling for the uplink,the channel estimation unit 105 estimates the uplink channel states fromuplink reference signals (for example, sounding reference signals) andoutputs the uplink channel states to the scheduling unit 104.

The receive data demodulation unit 106 demodulates the receive data. Thereceive data demodulation unit 106 performs signal processing such asDFT conversion, subcarrier mapping, or the IFFT conversion with respectto modulated data that are input from the radio unit 103 based onestimation results of the uplink channel states that are input from thechannel estimation unit 105, thereby applies a demodulation process tothe modulated data, and outputs the demodulated data to the dataextraction unit 107.

The data extraction unit 107 confirms whether the receive data inputfrom the receive data demodulation unit 106 are correct or incorrect andoutputs a confirmation result (for example, ACK or NACK) to thescheduling unit 104. Further, the data extraction unit 107 separates thedata input from the receive data demodulation unit 106 into thetransport channels and control data of the physical layers and outputsthose to the scheduling unit 104.

The higher layer 108 performs a process of a radio resource control(RRC) layer and a process of a medium access control (MAC) layer. Thehigher layer 108 integrally controls process units of lower layers.Thus, interfaces are present between the higher layer 108 and thescheduling unit 104, the antenna 109, the radio unit 103, the channelestimation unit 105, the receive data demodulation unit 106, the datacontrol unit 101, the transmit data modulation unit 102, and the dataextraction unit 107.

FIG. 2 is a schematic block diagram that illustrates a configuration ofa terminal device according to this embodiment. A terminal device 200 isconfigured to include a data control unit 201, a transmit datamodulation unit 202, a radio unit 203, a scheduling unit 204, a channelestimation unit 205, a receive data demodulation unit 206, a dataextraction unit 207, a higher layer 208, and an antenna 209. Further, atransmitting unit is configured with the data control unit 201, thetransmit data modulation unit 202, the radio unit 203, the schedulingunit 204, the higher layer 208, and the antenna 209. Further, areceiving unit is configured with the radio unit 203, the schedulingunit 204, the channel estimation unit 205, the receive data demodulationunit 206, the data extraction unit 207, the higher layer 208, and theantenna 209. Here, the units that configure the terminal device 200 mayalso be referred to as units.

The data control unit 201 receives the transport channels from thescheduling unit 204. The data control unit 201 maps signals generated bythe transport channels and the physical layers on the physical channelsbased on scheduling information that is input from the scheduling unit204. Mapped data are output to the transmit data modulation unit 202.

The transmit data modulation unit 202 modulates and codes the transmitdata. The transmit data modulation unit 202 performs signal processingsuch as modulation and coding, serial-parallel conversion of inputsignals, the IFFT process, and the CP insertion with respect to the datainput from the data control unit 201, generates the transmit data, andoutput the transmit data to the radio unit 203.

The radio unit 203 performs up-conversion of the transmit data inputfrom the transmit data modulation unit 202 into radio frequencies togenerate radio signals and transmits the radio signals to the basestation via the antenna 209. Further, the radio unit 203 receives theradio signals that are received from the base station via the antenna209, performs down-conversion of the radio signals into basebandsignals, and outputs the receive data to the channel estimation unit 205and the receive data demodulation unit 206.

The scheduling unit 204 performs mapping of the logical channels and thetransport channels, scheduling for the downlink and the uplink, and soforth. The scheduling unit 204 integrally controls process units of thephysical layers. Thus, interfaces are present between the schedulingunit 204 and the antenna 209, the data control unit 201, the transmitdata modulation unit 202, the channel estimation unit 205, the receivedata demodulation unit 206, and the data extraction unit 207, and theradio unit 203.

Further, the scheduling unit 204 performs reception control of thetransport channels and the physical channels and generation ofscheduling information based on downlink control information that isreceived from the base station, scheduling information that is inputfrom the higher layer 208, and so forth. The scheduling information thatis used for the scheduling for the downlink is output to the datacontrol unit 201.

Further, the scheduling unit 204 performs a scheduling process formapping uplink logical channels input from the higher layer 208 on thetransport channels and generation of scheduling information that is usedfor the scheduling for the uplink based on the downlink controlinformation that is received from the base station, the schedulinginformation that is input from the higher layer 208, and so forth. Thescheduling information is output to the data control unit 201.

Further, the scheduling unit 204 maps the uplink logical channels thatare input from the higher layer 208 to the transport channels andoutputs the uplink logical channels to the data control unit 201.Further, the scheduling unit 204 outputs channel state information thatis input from the channel estimation unit 205 and a confirmation resultof cyclic redundancy check (CRC) parity bits (simply referred to as CRCsalso) that are input from the data extraction unit 207 to the datacontrol unit 201.

In order to demodulate signals that are transmitted by the downlink, thechannel estimation unit 205 estimates downlink channel states fromdownlink reference signals and outputs the downlink channel states tothe receive data demodulation unit 206. Further, the receive datademodulation unit 206 demodulates the receive data that are input fromthe radio unit 203 and outputs the receive data to the data extractionunit 207.

Further, the receive data demodulation unit 206 receives the PDSCH thatis mapped to the resource element based on the resource element to whichthe physical signal or physical channel is mapped (also described asdemapping the PDSCH from the resource element). For example, the receivedata demodulation unit 206 receives downlink data on an assumption thatthe rate-matching is performed based on the position of thecell-specific reference signal that is determined in accordance with thephysical layer cell identity. Further, the receive data demodulationunit 206 receives the downlink data on an assumption that therate-matching is performed based on the position of the cell-specificreference signal or the resource element that is specified by the basestation device.

The data extraction unit 207 confirms whether the receive data inputfrom the receive data demodulation unit 206 are correct or incorrect andoutputs a confirmation result (for example, ACK or NACK) to thescheduling unit 204. Further, the data extraction unit 207 separates thereceive data input from the receive data demodulation unit 206 into thetransport channels and the control data of the physical layers andoutputs those to the scheduling unit 204.

The higher layer 208 performs a process of the radio resource controllayer and a process of the MAC layer. The higher layer 208 integrallycontrols process units of the physical layers. Thus, interfaces arepresent between the higher layer 208 and the scheduling unit 204, theantenna 209, the data control unit 201, the transmit data modulationunit 202, the channel estimation unit 205, the receive data demodulationunit 206, and the data extraction unit 207, and the radio unit 203.

FIG. 3 is a schematic diagram that illustrates an example of a radiocommunication system according to this embodiment. In FIG. 3, forexample, a terminal device 303 may perform single-cell communicationwith a primary base station 301 or a secondary base station 302.Further, the terminal device 303 may perform multi-cell communicationwith the primary base station 301 and/or the secondary base station 302.

Here, single-cell communication means that a single base station devicetransmits downlink information (a downlink signal) to a terminal device.For example, the terminal device 303 may receive downlink informationthat is transmitted from the primary base station 301 by a downlink 304by a certain subframe. Further, the terminal device 303 may receivedownlink information that is transmitted from the secondary base station302 by a downlink 305 by another certain subframe.

Further, multi-cell communication means that plural base station devicesmutually cooperate to transmit downlink information to a terminaldevice. For example, the terminal device 303 may receive downlinkinformation that is transmitted from the primary base station 301 by thedownlink 304 and downlink information that is transmitted from thesecondary base station 302 by the downlink 305 by a same subframe.

Further, for example, as dynamic point selection that will be describedbelow, the terminal device 303 may receive the downlink information thatis transmitted from the primary base station 301 by the downlink 304 orthe downlink information that is transmitted from the secondary basestation 302 by the downlink 305 by a same subframe. In the multi-cellcommunication that performs the dynamic point selection, the terminaldevice 303 may perform a receiving process without recognizing fromwhich base station device (transmitting point) the downlink informationis transmitted.

For example, the multi-cell communication includes a CoMP transmissionscheme. More specifically, the multi-cell communication includes jointtransmission (JT) (or joint processing) in which same downlinkinformation is transmitted from plural base station devices. Further,the multi-cell communication includes the dynamic point selection (DPS)that dynamically switches the base station devices that transmit thedownlink information. Further, the multi-cell communication includescoordinated beamforming (CB) in which the base station devices cooperateto perform beamforming to reduce mutual interference. Further, themulti-cell communication includes coordinated scheduling (CS) in whichthe base station devices cooperate to perform scheduling to reducemutual interference.

Here, for example, in a case where the joint transmission is used as themulti-cell communication, the terminal device 303 receives the downlinkinformation that is transmitted by the downlink 304 and the downlinkinformation that is transmitted by the downlink 305 by a certainsubframe. Further, in a case where the dynamic point selection is usedas the multi-cell communication, the terminal device 303 receives thedownlink information that is transmitted by the downlink 304 or thedownlink information that is transmitted by the downlink 305 by acertain subframe.

Further, communication between the base station devices (for example,interchange or the like of control information for performing themulti-cell communication or the single-cell communication) is performedthrough a line 306. For example, a wired line such as an optical fiberor a radio line such as a relay is used for the line 306.

Here, different physical layer cell identities (PCIs) (also referred toas physical layer cell identifiers) may be set for the primary basestation 301 and the secondary base station 302. Further, a same physicallayer cell identity may be set for all or a unit of the primary basestation 301 and the secondary base station 302.

Here, the downlink information includes downlink data (downlink sharedchannel (DL-SCH)). Further, the downlink information includesinformation (multicast channel (MCH)) about Multimedia Broadcast andMulticast Service (MBMS). Further, the downlink information includesdownlink control information (DCI).

Here, the DL-SCH and the MCH are the transport channels. Further,channels that are used for the medium access control (MAC) layer arereferred to as transport channels. Further, a unit of the transportchannels that are used in the MAC layer is referred to as transportblock.

Further, the DL-SCH is mapped to the physical downlink shared channel(PDSCH). That is, the PDSCH is used to transmit the downlink data.

Further, the MCH is mapped to the physical multicast channel (PMCH).That is, the PMCH is used to transmit the information about the MBMS.

Further, the downlink control information is mapped to a physicaldownlink control channel (PDCCH). That is, the PDCCH is used to transmitthe downlink control information.

Further, the downlink control information may be mapped to an enhancedphysical downlink control channel (E-PDCCH) (a PDCCH that is enhanced).That is, the E-PDCCH is used to transmit the downlink controlinformation.

Here, in a case where the base station device transmits the downlinkinformation to the terminal device, the base station device multiplexesthe downlink reference signals (DRSs) that are known signals between thebase station device and the terminal device to transmit. For example,four types that will be described below are defined as the downlinkreference signals. Here, the downlink reference signals are physicalsignals.

For example, cell-specific reference signals (CRSs) are defined as thedownlink reference signals. Here, the cell-specific reference signalsare also referred to as common reference signals (CRSs).

For example, the cell-specific reference signals are used by theterminal device for synchronization in downlink frequency domain andtime domain. Further, the cell-specific reference signals are used toperform channel correction to the PDCCH. Further, the cell-specificreference signals are used to perform channel correction to the PDSCH.Further, the cell-specific reference signals are used by the terminaldevice for calculation of the downlink channel state information.

Further, the cell-specific reference signals are transmitted to pluralterminal devices as targets. Further, the cell-specific referencesignals are transmitted over all bands of the downlink. Further, thecell-specific reference signals are transmitted in all downlinksubframes that support transmission of the PDSCH.

In addition, user equipment-specific reference signals (URSs) (alsoreferred to as terminal-device-specific reference signals) are definedas the downlink reference signals. Here, the user equipment-specificreference signals are also referred to as demodulation reference signals(DMRSs).

For example, the user equipment-specific reference signals are used sothat the terminal device performs channel correction to the E-PDCCH.Further, the user equipment-specific reference signals are used so thatthe terminal device performs channel correction to the PDSCH. Further,the user equipment-specific reference signals are transmitted to aspecified terminal device as a target. Further, the userequipment-specific reference signals are transmitted only in resourceblocks that are used for transmission of the PDSCH to a correspondingterminal device as a target.

Here, the user equipment-specific reference signals that are associatedwith the E-PDCCH may be different from the user equipment-specificreference signals that are associated with the PDSCH. For example, theantenna port that is used by the user equipment-specific referencesignals associated with the E-PDCCH may be different from the antennaport that is used by the user equipment-specific reference signalsassociated with the PDSCH.

In addition, Multicast/Broadcast over Signal Frequency Network referencesignals (MBSFN reference signals; MBSFN RSs) are defined as the downlinkreference signals.

For example, the MBSFN reference signals are used so that the terminaldevice performs channel correction to the PMCH. Further, the MBSFNreference signals are transmitted to plural terminal devices as targets.Further, the MBSFN reference signals are transmitted over all the bandsof the downlink. Further, the MBSFN reference signals are transmitted insubframes that are configured as MBSFN subframes by the base stationdevice by using higher layer signaling.

That is, the base station device may configure subsets of a downlinksubframe in a radio frame as the MBSFN subframes. Here, the MBSFNsubframe represents a subframe that is reserved for the MBSFN subframe.For example, the MBSFN subframe is indicated for each serving cell basedon parameters (hereinafter referred to as information about the MBSFNsubframe also) that are transmitted by the base station device by usingthe higher layer signaling.

Here, the downlink subframes in the radio frame that are not configuredas the MBSFN subframes are referred to as non-MBSFN subframes or unicastsubframes.

For example, the base station device may perform transmission on thePDSCH but may not perform transmission on the PMCH in the non-MBSFNsubframe. Further, the base station device may perform transmission onthe PDSCH or the PMCH in the MBSFN subframe. The terminal device decodesthe PDSCH in the MBSFN subframe other than the subframe that areindicated for decoding of the PMCH by using the higher layer signaling.

Further, each of the MBSFN subframes is divided into a non-MB SFN areaand an MBSFN area. For example, the non-MBSFN area is configured withfirst one or two OFDM symbols in the MBSFN subframe. Further, the MBSFNarea is configured with OFDM symbols in the MBSFN subframe that are notused as the non-MBSFN area.

Here, the non-MBSFN area is an area that is not reserved for an MBSFN.Further, the MBSFN area is an area that is reserved for the MBSFN. Thatis, the PMCH is transmitted only in the MBSFN area in a certain MBSFNsubframe. Further, the PDSCH is transmitted only in the MBSFN area in acertain MBSFN subframe.

In addition, channel state information reference signals (CSI-RSs) aredefined as the downlink reference signals.

For example, the channel state information reference signals are used bythe terminal device for calculation of downlink channel stateinformation. Here, the channel state information reference signals aretransmitted only by bands that are configured by the base stationdevice.

In addition, in FIG. 3, aggregation of plural serving cells (simplyreferred to as cells also) is supported in the downlink and the uplink(which is referred to as carrier aggregation (CA) or cell aggregation(CA)). Here, in the carrier aggregation, one serving cell is defined asa primary cell (Pcell). Further, in the carrier aggregation, the servingcells other than the primary cell are defined as secondary cells(Scells).

Here, the serving cells may be defined as one serving cell (cell) thatis formed with the primary cell with respect to the terminal for whichthe CA is not configured. Further, the serving cells may be defined as aset of (one or) plural serving cells (cells) that are formed with theprimary cell and the secondary cells with respect to the terminal forwhich the CA is configured.

Here, a carrier that corresponds to the serving cell in the downlink isdefined as a downlink component carrier (DLCC). Further, a carrier thatcorresponds to the primary cell in the downlink is defined as a downlinkprimary component carrier (DLPCC). Further, a carrier that correspondsto the secondary cell in the downlink is defined as a downlink secondarycomponent carrier (DLSCC).

Further, a carrier that corresponds to the serving cell in the uplink isdefined as an uplink component carrier (ULCC). Further, a carrier thatcorresponds to the primary cell in the uplink is defined as an uplinkprimary component carrier (ULPCC). Further, a carrier that correspondsto the secondary cell in the uplink is defined as an uplink secondarycomponent carrier (ULSCC).

For example, the primary cell is defined as a cell in which the terminaldevice performs an initial connection establishment procedure. Further,the primary cell is defined as a cell in which the terminal devicestarts a connection re-establishment procedure. Further, the primarycell is defined as a cell that is indicated as the primary cell by thebase station device in a handover procedure.

That is, the base station device and the terminal device may performtransmission and reception on plural physical channels in a certainsubframe. Here, each of the physical channels is mapped to any one ofthe serving cells. That is, a single physical channel is not mapped tothe plural serving cells.

FIG. 4 is a diagram that illustrates an example of mapping of physicaldownlink channels. FIG. 4 illustrates resource areas of the PDCCHs,resource areas of the E-PDCCHs, resource areas of the PDSCHs, andresource areas of the PMCHs. Further, common search spaces (CSSs) anduser equipment-specific search spaces (UE-specific search spaces (USSs))(terminal-device-specific search spaces) are illustrated.

As illustrated in FIG. 4, the PDSCH is mapped to the OFDM symbols (thatmay be resource elements for the OFDM symbols) to which the PDCCH is notmapped in the non-MBSFN subframe. Further, the PDSCH is mapped to theOFDM symbols to which the PDCCH is not mapped in the MBSFN subframe.

Further, the PMCH is mapped to the MBSFN area in the MBSFN subframe.Here, a single PMCH is transmitted in a certain subframe.

For example, the PDCCH is mapped to the OFDM symbols of numbers 0, 1,and 2 in the non-MB SFN subframe. Further, for example, the PDCCH ismapped to the OFDM symbols of numbers 0 and 1 in the MBSFN subframe.Here, the PDCCH may be multiplexed with the PDSCH by time divisionmultiplex (TDM).

Here, the base station device may indicate information about the OFDMsymbols that are used for transmission of the PDCCH in a certainsubframe to the terminal device by using a physical control formatindicator channel (PDFICH). Further, the PDCCH may be transmitted byusing the antenna port that is the same as the antenna port used fortransmission of the cell-specific reference signals.

Further, the E-PDCCH is mapped to the OFDM symbols to which the PDCCH isnot mapped in a certain subframe. Further, the E-PDCCH may bemultiplexed with the PDSCH by frequency division multiplex (FDM).

Here, for example, the base station device may configure the resourcearea of the E-PDCCH for the terminal device by using the higher layersignaling. Further, the E-PDCCH may be transmitted by using the antennaport that is the same as or different from the antenna port used fortransmission of the user equipment-specific reference signals that areassociated with the PDSCH. Here, the user equipment-specific referencesignals may be shared by plural terminal devices. Hereinafter, theE-PDCCH is basically included in the PDCCH.

Here, plural formats (downlink control information (DCI) formats) aredefined for the downlink control information that is transmitted on thePDCCH and/or the E-PDCCH.

For example, a DCI format 1A that is used for scheduling of a singlePDSCH in a single cell (transmission of a single PDSCH codeword and asingle downlink transport block) is defined as the DCI format for thedownlink.

Further, a DCI format 2 (that may be a DCI format 2C) that is used forscheduling of a single PDSCH in a single cell (transmission of two orless PDSCH codewords and two or less downlink transport blocks) isdefined as the DCI format for the downlink.

Further, for example, a DCI format (DCI format X) that is used forscheduling for the multi-cell communication is defined as the DCI formatfor the downlink.

For example, the DCI format for the downlink includes the downlinkcontrol information such as information about resource allocation forthe PDSCH and information about a modulation and coding scheme (MCS).Hereinafter, the DCI format that is used for the scheduling of the PDSCHwill also be denoted as downlink assignment.

Further, for example, a DCI format 0 that is used for scheduling of asingle physical uplink shared channel (PUSCH) in a single cell(transmission of a single PUSCH codeword and a single uplink transportblock) is defined as the DCI format for the uplink.

Further, a DCI format 4 that is used for scheduling of a single PUSCH ina single cell (transmission of two or less PUSCH codewords and two orless uplink transport block) is defined as the DCI format for theuplink.

Further, for example, a DCI format (DCI format Y) that is used forscheduling for the multi-cell communication may be defined as the DCIformat for the uplink.

For example, the DCI format for the uplink includes the downlink controlinformation such as information about resource allocation for the PUSCHand information about the modulation and coding scheme (MCS).Hereinafter, the DCI format that is used for the scheduling of the PUSCHwill also be denoted as uplink grant.

Further, the terminal device monitors a set of PDCCH candidates. Here,the PDCCH candidate means a candidate to which the PDCCH may be mappedand on which the PDCCH may be transmitted by the base station device.Further, the PDCCH candidate is configured with a single or pluralcontrol channel elements (CCEs). Further, monitoring means that theterminal device attempts to decode each of the PDCCHs in the set ofPDCCH candidates in accordance with all the DCI formats that aremonitored.

Further, the terminal device monitors a set of E-PDCCH candidates. Here,the E-PDCCH candidate means a candidate to which the E-PDCCH may bemapped or on which the E-PDCCH may be transmitted by the base stationdevice. Further, the E-PDCCH candidate is configured with a single orplural enhanced control channel elements (E-CCEs). Further, monitoringmeans that the terminal device attempts to decode each of the E-PDCCHsin the set of E-PDCCH candidates in accordance with all the DCI formatsthat are monitored.

Here, the set of PDCCH candidates and/or the set of E-PDCCH candidatesthat are monitored by the terminal device are also referred to as asearch space. That is, the search space is a set of resources that maybe used by the base station device for transmission of the PDCCH and/ortransmission of the E-PDCCH.

That is, the CSS and/or the USS are configured (defined or set) in theresource area of the PDCCH. Further, the CSS and/or the USS areconfigured (defined or set) in the resource area of the E-PDCCH.

The base station device transmits (allocates) the PDCCH in the CSSand/or the USS in the resource area of the PDCCH. Further, the basestation device transmits (allocates) the E-PDCCH in the CSS and/or theUSS in the resource area of the E-PDCCH.

Further, the terminal device monitors the PDCCH in the CSS and/or theUSS in the resource area of the PDCCH and detects the PDCCH addressed tothe own device. Further, the terminal device monitors the E-PDCCH in theCSS and/or the USS in the resource area of the E-PDCCH and detects theE-PDCCH addressed to the own device.

Here, the CSS is used for transmission of the downlink controlinformation to plural terminal devices. That is, the CSS is defined ascommon resources with respect to the plural terminal devices. Forexample, the CSSs are configured with the CCEs of predetermined numbers(for example, the CCEs of indices 0 to 15) between the base stationdevice and the terminal devices.

Further, the CSS may be used for transmission of the downlink controlinformation to a specified terminal device. That is, the base stationdevice may transmit the DCI format for the plural terminal devices astargets and/or the DCI format for a specified terminal device as atarget in the CSS.

Further, the USS is used for transmission of the downlink controlinformation to a specified terminal device. That is, the USS is definedas dedicated resources with respect to a certain terminal device. Thatis, the USS is independently defined with respect to the respectiveterminal devices. For example, the USS is configured with the CCE of anumber that is determined based on a radio network temporary identifier(RNTI) that is assigned by the base station device, a slot number in theradio frame, an aggregation level, and so forth. That is, the basestation device transmits the DCI format for a specified terminal deviceas a target in the USS.

Here, the RNTI that is assigned to the terminal device by the basestation device is used for transmission of the downlink controlinformation (transmission on the PDCCH or transmission on the E-PDCCH).Specifically, the cyclic redundancy check (CRC) parity bits (simplyreferred to as CRCs also) that are generated based on the downlinkcontrol information (that may be the DCI format) are attached to thedownlink control information. After the attachment, the CRC parity bitsare scrambled by the RNTI.

That is, the terminal device attempts to decode the PDCCH (that may bethe E-PDCCH, the downlink control information, or the DCI formats) withthe CRC parity bits that are scrambled by the RNTI and detects the PDCCHwith which the CRC is successful as the PDCCH addressed to the owndevice (also referred to as blind decoding).

Here, the RNTI includes a cell RNTI (C-RNTI). Further, the RNTI includesa random access RNTI (RA-RNTI).

Further, the RNTI includes a paging RNTI (P-RNTI). Further, the RNTIincludes a system information RNTI (SI-RNTI).

Here, the C-RNTI is a unique identifier that is used for identificationof radio resource control (RRC) connection and scheduling. For example,the C-RNTI is used for unicast transmission that is dynamicallyscheduled.

Further, the RA-RNTI is an identifier that is used in a case where arandom access response message is transmitted in a random accessprocedure. For example, the terminal device monitors the PDCCH with theCRC scrambled by the RA-RNTI in a case where a random access preamble istransmitted.

For example, the terminal device executes the random access procedurefor initial connection establishment. Further, the terminal deviceexecutes the random access procedure for the handover. Further, theterminal device executes the random access procedure for connectionre-establishment. Further, the terminal device executes the randomaccess procedure to request a resource for a UL-SCH.

Further, the P-RNTI is an identifier that is used for paging andnotification of system information. Further, the SI-RNTI is anidentifier that is used for broadcasting the system information.

Here, the PDCCH with the CRC scrambled by the C-RNTI may be transmittedin the USS or the CSS. Further, the PDCCH with the CRC scrambled by theRA-RNTI may be transmitted only in the CSS. Further, the PDCCH with theCRC scrambled by the P-RNTI may be transmitted only in the CSS. Further,the PDCCH with the CRC scrambled by the SI-RNTI may be transmitted onlyin the CSS.

That is, the terminal device changes an interpretation of the downlinkcontrol information based on by which RNTI the CRC is scrambled.Further, the terminal device receives the downlink data on the PDSCHthat is scheduled by using the downlink control information transmittedon the PDCCH. Hereinafter, the transmission of the downlink data on thePDSCH will also be denoted as transmission of the PDSCH. Further, thereception of the downlink data on the PDSCH will also be denoted asreception of the PDSCH.

Further, the base station device and the terminal device transmit andreceive signals in the higher layers. For example, the base stationdevice and the terminal device transmit and receive a radio resourcecontrol signal (RRC signaling) (also referred to as a radio resourcecontrol (RRC) message or a radio resource control (RRC) information) inan RRC layer (layer 3).

Here, a dedicated signal that is transmitted to a certain terminaldevice by the base station device in the RRC layer is also referred toas dedicated signal. That is, a dedicated (specific) configuration(information) for a certain terminal device is transmitted by using thededicated signal by the base station device. Hereinafter, the dedicatedsignals are included in the RRC signaling.

Further, the base station device and the terminal device transmit andreceive a MAC control element in a medium access control (MAC) layer(layer 2). Here, the RRC signaling and/or the MAC control element arealso referred to as higher layer signaling.

FIG. 5 is a diagram that illustrates an example of mapping of the PDSCHand the downlink reference signals. FIG. 5 illustrates an example ofmapping of the downlink reference signals in the non-MB SFN subframe.Here, FIG. 5 illustrates two resource blocks (also referred to asresource block pair) in one subframe. For example, 1 resource block isconfigured with 12 subcarriers in the frequency domain and with 7 OFDMsymbols in the time domain.

Here, each of the seven OFDM symbols in the time domain in one subframeis also referred to as slot. That is, one subframe is configured with afirst slot and a second slot. Further, a resource (a minimumtime-frequency configuration unit) that is defined by one OFDM symboland one subcarrier in one slot is also referred to as a resourceelement. That is, the PDSCH is mapped to the resource elements. Further,the downlink reference signals are mapped to the resource elements.

Here, in FIG. 5, Ri represents the resource elements to which thecell-specific reference signals for an antenna port i are mapped (orwhich are used for transmission of the cell-specific reference signals)(for example, i=0, 1, 2, 3).

Further, Di represents the resource elements to which the userequipment-specific reference signals for a DMRS group i are mapped(which are used for transmission of the user equipment-specificreference signals) (for example, i=1, 2).

Here, for example, the antenna ports of the user equipment-specificreference signals that are associated with the PDSCH are 7 to 14.Further, for example, the antenna ports of the user equipment-specificreference signals that are associated with the E-PDCCH are 107 to 110.Further, the user equipment-specific reference signal for each of theantenna ports is generated with an orthogonal code sequence with a codelength of two or four and is mapped to the resource element of any ofthe DMRS groups.

Further, Ci represents the resource elements to which the channel stateinformation reference signals for a CSI-RS group i are mapped (which areused for transmission of the channel state information referencesignals) (for example, i=1, 2, 3, 4).

Here, for example, the antenna ports of the channel state informationreference signals are 15 to 22. Further, the channel state informationreference signal for each of the antenna ports is generated with theorthogonal code sequence with a code length of two and is mapped to theresource element of any of the CSI-RS groups.

FIG. 6 is another diagram that illustrates an example of mapping of thePDSCH and the downlink reference signals. FIG. 6 illustrates an exampleof mapping of the downlink reference signals in the MBSFN subframe.

As illustrated in FIG. 6, in a certain MBSFN subframe, the cell-specificreference signals are not transmitted in the MBSFN area in the MBSFNsubframe. That is, in a certain MBSFN subframe, the cell-specificreference signals are transmitted only in the non-MBSFN area in theMBSFN subframe.

For example, the user equipment-specific reference signals aretransmitted in the MBSFN area in a certain MBSFN subframe. Further, theMBSFN reference signals are transmitted in the MBSFN area in a certainMBSFN subframe in a case where the PMCH is transmitted.

FIG. 7 is another diagram that illustrates an example of mapping of thePDSCH and the downlink reference signals. Here, FIG. 7 illustrates anexample of mapping of the downlink reference signals that aretransmitted in each of two cells.

Here, the left side of FIG. 7 illustrates an example of mapping of thedownlink reference signals that are transmitted in a certain cell (cell1). Further, the right side of FIG. 7 illustrates an example of mappingof the downlink reference signals that are transmitted in a cell (cell2) with the physical layer cell identity that is different from thephysical layer cell identity of the cell 1. Here, for example, the cell2 that is indicated on the right side of FIG. 7 may be considered as aneighboring cell (also referred to as other cell, coordinated cell, orassociated cell) of the cell 1.

For example, the terminal device may assume (identify and recognize)each of the downlink reference signals that are illustrated in FIG. 7.That is, for example, the terminal device receives the PDSCHs based onthe respective positions of two cell-specific reference signals.

Here, the positions of the cell-specific reference signals (hereinafterdenoted as CRS positions also) is determined (calculated) based on thephysical layer cell identity (a value of the physical layer cellidentity). Here, the positions of the cell-specific reference signalsare also denoted as the resource elements (the positions of the resourceelements) to which the cell-specific reference signals are mapped.

For example, the positions of the cell-specific reference signals in thecell 1 are determined based on the physical layer cell identity of thecell 1. Further, the positions of the cell-specific reference signals inthe cell 2 are determined based on the physical layer cell identity ofthe cell 2. That is, as illustrated in FIG. 7, the cell-specificreference signals are mapped to different positions with respect to thecells (cell 1 and cell 2) with the different physical layer cellidentities.

For example, the positions of the cell-specific reference signals aredetermined by specifying the positions of the resource elements to whichthe cell-specific reference signals are mapped based on the physicallayer cell identity. Further, for example, the positions of thecell-specific reference signals are shifted in the frequency directionbased on the physical layer cell identity. Further, for example, thepositions of the cell-specific reference signals are determined in threepatterns with respect to the frequency direction based on the physicallayer cell identity.

Here, for example, the terminal device may detect the physical layercell identity by using synchronization signals. Further, the terminaldevice may obtain the physical layer cell identity from information thatis included in the higher layer signaling (for example, a handovercommand) that is transmitted by the base station device.

FIG. 8 is another diagram that illustrates an example of mapping of thePDSCH and the downlink reference signals. Here, FIG. 8 illustrates anexample of mapping of the downlink reference signals that aretransmitted from the two cells. Further, the cell 1 and the cell 2 thatare illustrated in FIG. 8 correspond to FIG. 7. For example, theterminal device may assume (identify and recognize) the downlinkreference signals that are illustrated in FIG. 8 in a case where themulti-cell communication is performed by the cell 1 and the cell 2. Thatis, the terminal device receives the PDSCH based on the positions of twocell-specific reference signals.

Here, in a case where physical signals or physical channels (forexample, cell-specific reference signals or the like) other than thePDSCH are mapped to the resource elements when the PDSCH is mapped tothe resource element, the rate-matching is performed for the PDCCH withrespect to the resource elements to which the physical signals orphysical channels are mapped.

Here, the rate-matching means a process in which the PDSCH is mappedwhile avoiding the resource elements to which physical signals orphysical channels other than the PDSCH are mapped. For example, aprocess different from the rate-matching may be puncturing (puncturingprocess) in which a physical signal or physical channel other than thePDSCH is mapped by overwriting the physical signal or physical channelto the resource element to which the PDSCH is mapped.

That is, the PDSCH is mapped to the resource elements except theresource elements to which the physical signals or physical channelsother than the PDSCH are mapped. That is, the PDSCH is mapped to theresource elements that are not used for the physical signals or physicalchannels other than the PDSCH.

Here, in a case where the terminal device receives the PDSCH withoutassuming that the rate-matching is performed by the base station deviceand transmission on the PDSCH is performed, reception performance forthe PDSCH degrades. Thus, in order to avoid degradation of the receptionperformance for the PDSCH, the base station device and the terminaldevice preferably perform transmission and reception on the PDSCH basedon the resource elements to which the physical signals or physicalchannels other than the PDSCH are mapped.

Here, to simplify the description, FIGS. 7 and 8 illustrate an operation(process) of the base station device and the terminal device based onthe two cell-specific reference signals. However, it is matter of coursethat similar embodiments are applicable regardless of the number of thecell-specific reference signals.

For example, the base station device may perform the rate-matching forthe PDSCH based on the positions of three cell-specific referencesignals. Further, the terminal device may receive the PDSCH based on thepositions of three cell-specific reference signals.

Here, the base station device may indicate (configure or specify) thepositions of the cell-specific reference signals for the terminal. Forexample, the base station device may independently indicate therespective positions of one or more cell-specific reference signals (forexample, the respective positions of three cell-specific referencesignals). That is, the base station device may indicate the resourceelements (the positions of the resource elements) that are available fortransmission of the PDSCH for the terminal device.

Here, for example, the positions of the cell-specific reference signalsmay be determined based on a frequency shift (positions in the frequencydirection) of the cell-specific reference signals. As described above,the frequency shift of the cell-specific reference signals is determinedbased on the physical layer cell identity. Further, the positions of thecell-specific reference signals may be determined based on the number ofports that are used for transmission of the cell-specific referencesignals. Further, presence or absence of the cell-specific referencesignals may be determined based on whether or not the subframe is theMBSFN subframe.

That is, the base station device transmits information that indicatesthe frequency shift of the cell-specific reference signals (for example,information about the physical layer cell identity) and may therebyindicate the positions of the cell-specific reference signals. Further,the base station device transmits information that indicates the numberof the ports of the cell-specific reference signals and may therebyindicate the positions of the cell-specific reference signals.

Further, the base station device transmits information that indicatesthe subframe in which the cell-specific reference signals is transmitted(for example, information about the MBSFN subframe) and may therebyindicate presence or absence of the cell-specific reference signals.

Hereinafter, the information that indicates the frequency shift of thecell-specific reference signals, and/or the information that indicatesthe number of the ports of the cell-specific reference signals, and/orthe information that indicates the subframe in which the cell-specificreference signals is transmitted are also denoted as information thatindicates the positions of the cell-specific reference signals.

For example, the base station device may transmit the higher layersignaling (that may also be the dedicated signals) that includes theinformation that indicates the positions of the cell-specific referencesignals. That is, the base station device may configure a set of thepositions of the resource elements to which the cell-specific referencesignals are mapped.

Further, the base station may use the higher layer signaling (that maybe the dedicated signal) to configure a plurality of sets of thepositions of the cell-specific reference signals and may further use thePDCCH to indicate one or a plurality of positions of the cell-specificreference signals from the configured plurality of positions of thecell-specific reference signals.

Further, the base station may use the higher layer signaling (that maybe the dedicated signals) to configure a plurality of sets of thepositions of the cell-specific reference signals and may further use thePDCCH to indicate whether the configuration is valid or invalid.

That is, the base station device may transmit on the PDCCH, the DCIformat (for example, the downlink assignment) that includes the downlinkcontrol information about the positions of the cell-specific referencesignals (hereinafter referred to as first control information also) tothe terminal device. For example, a field of two bits (or a field ofthree bits) that is defined in the DCI format is mapped to the firstcontrol information.

For example, in a case where the field of two bits that is defined inthe DCI format is mapped to the first control information, three statesamong four states may be used to indicate the positions of thecell-specific reference signals (for example, “01: set 1 of thepositions of the cell-specific reference signals”, “10: set 2 of thepositions of the cell-specific reference signals”, and “11: set 3 of thepositions of the cell-specific reference signals”).

In this case, the base station device may use one remaining state toindicate the positions of the cell-specific reference signals of theserving cell (that is, using the positions of the cell-specificreference signal that are determined based on the physical layer cellidentity) (for example, “00: the positions of the cell-specificreference signals of the serving cell”).

Further, in a case where the field of three bits that is defined in theDCI format is mapped to the information about the positions of thecell-specific reference signals, the (three) positions of thecell-specific reference signals may be indicated by using a bitmapformat. That is, a combination of the three positions of thecell-specific reference signals are made correspond to the bits of thefield of three bits, thereby enabling indication of the combination ofthe three positions of the cell-specific reference signals.

Here, for example, the first control information may be included in theDCI format other than a predetermined DCI format. That is, the firstcontrol information may not be included in the predetermined DCI format.For example, the first control information may not be included in theDCI format 1A. Here, the DCI format (the predetermined DCI format) thatmay include the first control information is defined in advance by aspecification or the like.

Further, the first control information may be included in the DCI formatin a case where the DCI format is transmitted in the USS. That is, thefirst control information may not be included in the DCI format in acase where the DCI format is transmitted in the CSS.

For example, the first control information may be included in the DCIformat 1A in a case where the DCI format 1A is transmitted in the USS.Further, the first control information may not be included in the DCIformat 1A in a case where the DCI format 1A is transmitted in the CSS.

Further, the first control information may be included in the DCI formatthat is transmitted only in the USS. That is, the first controlinformation may not be included in the DCI format that is transmitted inthe CSS.

Further, the first control information may be included in the DCI formatin a case where the DCI format is transmitted on the PDCCH with the CRCscrambled by the C-RNTI. That is, the first control information may notbe included in the DCI format in a case where the DCI format istransmitted on the PDCCH with the CRC scrambled by the RA-RNTI. Further,the first control information may not be included in the DCI format in acase where the DCI format is transmitted on the PDCCH with the CRCscrambled by the P-RNTI. Further, the first control information may notbe included in the DCI format in a case where the DCI format istransmitted on the PDCCH with the CRC scrambled by the SI-RNTI.

Further, the first control information may be included in the DCI formatonly in a case where such a configuration is made by the base stationdevice. For example, the base station device may transmit informationabout whether or not first control information is included in the DCIformat by using the higher layer signaling (that may also be thededicated signals).

Further, the first control information may be included in the DCI formatonly in a case where such a predetermined transmission mode (forexample, a transmission mode for the PDSCH) is configured by the basestation device. For example, the base station device may transmit theDCI format that includes the first control information only in a casewhere the predetermined transmission mode is configured. Here, thepredetermined transmission mode is defined in advance by a specificationor the like.

Here, for example, the terminal may determine (assume) the positions ofthe cell-specific reference signals even in a case where informationabout the frequency shift of the cell-specific reference signal is nottransmitted.

For example, the terminal device may determine the positions of thecell-specific reference signals while assuming that the cell-specificreference signals are mapped to all the resource elements to which thecell-specific reference signals may be mapped. Further, the terminaldevice may determine the positions of the cell-specific referencesignals while assuming that the cell-specific reference signals aremapped to all the resource elements to which the cell-specific referencesignals may be mapped except the resource elements to which thecell-specific reference signals of the serving cells are mapped.Further, the terminal device may determine the positions of thecell-specific reference signals while assuming that the respectivepositions of plural cell-specific reference signals are the same as thepositions of the cell-specific reference signals of the serving cells.

Here, a manner of how the terminal device makes an assumption about theresource elements to which the cell-specific reference signals aremapped is defined in advance by a specification document or the like.

Further, the terminal device may determine (assume) the positions of thecell-specific reference signals even in a case where information aboutthe number of the ports of the cell-specific reference signals is nottransmitted.

For example, the terminal device may determine the positions of thecell-specific reference signals while assuming the number of the portsthat are used for the cell-specific reference signal. For example, theterminal device may determine the positions of the cell-specificreference signals while assuming that the number of the ports that areused for transmission of the cell-specific reference signals is any ofone port, two ports, and four ports. Further, the terminal device maydetermine the positions of the cell-specific reference signals whileassuming that the number of the ports that are used for transmission ofthe respective cell-specific reference signals of plural cells are thesame as the number of the ports that are used for transmission of thecell-specific reference signals of the serving cells.

Here, a manner of how the terminal device makes an assumption about thenumber of the ports that are used for transmission of the cell-specificreference signals is defined in advance by a specification document orthe like.

Further, the terminal device may determine (assume) the positions of thecell-specific reference signals even in a case where information thatindicates the subframe in which the cell-specific reference signals istransmitted is not transmitted.

For example, the terminal device may determine the positions of thecell-specific reference signals while assuming that the cell-specificreference signals are transmitted in all the subframes. Further, theterminal device may determine the positions of the cell-specificreference signals while assuming that the subframes in which therespective cell-specific reference signals of plural cells aretransmitted are the same as the subframes in which the cell-specificreference signals of the serving cells are transmitted.

Here, a manner of how the terminal device makes an assumption about thesubframes in which the cell-specific reference signals are transmittedis defined in advance by a specification document or the like.

As described above, the base station device performs the rate-matchingbased only on the positions of the cell-specific reference signals thatare determined in accordance with the physical layer cell identity ofthe serving cell and transmits the PDSCH (hereinafter denoted astransmission on the PDSCH based on the PCI also).

For example, as illustrated on the left side of FIG. 7, the base stationdevice performs the rate-matching based only on the positions of thecell-specific reference signals that are determined in accordance withthe physical layer cell identity of the cell 1 and transmits the PDSCH.Further, as illustrated on the right side of FIG. 7, the base stationdevice performs the rate-matching based only on the positions of thecell-specific reference signals that are determined in accordance withthe physical layer cell identity of the cell 2 and transmits the PDSCH.

Further, the base station device performs the rate-matching based on thepositions of the cell-specific reference signals that are indicated byusing a user-equipment specific configuration (also denoted as adedicated (specific) configuration for a certain terminal device) andtransmits the PDSCH (hereinafter denoted as transmission on the PDSCHbased on a first configuration also).

For example, as illustrated in FIG. 8, the base station device performsthe rate-matching based on the positions of the two cell-specificreference signals and transmits the PDSCH. For example, the base stationdevice performs the rate-matching based on the positions of thecell-specific reference signals that are transmitted in the cell 1 andthe positions of the cell-specific reference signals that is transmittedin the cell 2 and transmits the PDSCH.

Here, the base station device may perform the rate-matching based on thepositions of the cell-specific reference signals that are determined inaccordance with the physical layer cell identity of the serving cell andthe positions of the cell-specific reference signals that are indicatedfor the terminal device and may transmit the PDSCH. That is, the basestation device may perform the rate-matching based on the positions ofthe cell-specific reference signals that are indicated for the terminaldevice in addition to the positions of the cell-specific referencesignals that is determined in accordance with the physical layer cellidentity of the serving cell and may transmit the PDSCH.

Hereinafter, to simplify the description, a case where the rate-matchingis performed based on the positions of the cell-specific referencesignals that are indicated for the terminal device and transmission onthe PDSCH is performed will be described as transmission on the PDSCHbased on the first configuration.

However, the transmission on the PDSCH based on the first configurationincludes a case where the rate-matching is performed based on thepositions of the cell-specific reference signals that are indicated forthe terminal device in addition to the positions of the cell-specificreference signals that are determined in accordance with the physicallayer cell identity of the serving cell and transmission on the PDSCH isperformed. That is, the transmission on the PDSCH based on the firstconfiguration includes at least a case where the rate-matching isperformed based on the positions of the cell-specific reference signalsthat are indicated for the terminal device and transmission on the PDSCHis performed.

Further, the terminal device receives the PDSCH while assuming that therate-matching is performed based only on the positions of thecell-specific reference signals that are determined in accordance withthe physical layer cell identity of the serving cell (which willhereinafter be denoted as reception on the PDSCH based on the PCI also).

For example, as illustrated on the left side of FIG. 7, the terminaldevice receives the PDSCH while assuming that the rate-matching isperformed based only on the positions of the cell-specific referencesignals that are determined in accordance with the physical layer cellidentity of the cell 1. Further, as illustrated on the right side ofFIG. 7, the terminal device receives the PDSCH while assuming that therate-matching is performed based only on the positions of thecell-specific reference signals that are determined in accordance withthe physical layer cell identity of the cell 2.

Further, the terminal device receives the PDSCH while assuming that therate-matching is performed based only on the positions of thecell-specific reference signals that are indicated by using theuser-equipment specific configuration (which will hereinafter bereferred to as reception on the PDSCH based on the first configuration).

For example, as illustrated in FIG. 8, the terminal device receives thePDSCH while assuming that the rate-matching is performed based on thepositions of the two cell-specific reference signals. For example, theterminal device receives the PDSCH while assuming that the rate-matchingis performed based on the positions of the cell-specific referencesignals that are transmitted in the cell 1 and the positions of thecell-specific reference signals that are transmitted in the cell 2.

Here, the terminal device may receive the PDSCH while assuming that therate-matching is performed based on the positions of the cell-specificreference signals that are determined in accordance with the physicallayer cell identity of the serving cell and the positions of thecell-specific reference signals that are indicated by the base station.That is, the terminal device may receive the PDSCH while assuming thatthe rate-matching is performed based on the positions of thecell-specific reference signals that are indicated by the base stationdevice in addition to the positions of the cell-specific referencesignals that are determined in accordance with the physical layer cellidentity of the serving cell.

Hereinafter, to simplify the description, a case where reception on thePDSCH is performed on an assumption that the rate-matching is performedbased on the positions of the cell-specific reference signals that areindicated by the base station device will be described as reception onthe PDSCH based on the first configuration.

However, the reception on the PDSCH based on the first configurationincludes a case where the reception on the PDSCH is performed on anassumption that the rate-matching is performed based on the positions ofthe cell-specific reference signals that are indicated by the basestation device in addition to the positions of the cell-specificreference signals that are determined in accordance with the physicallayer cell identity of the serving cell. That is, the reception on thePDSCH based on the first configuration includes at least a case wherereception on the PDSCH is performed on an assumption that therate-matching is performed based on the positions of the cell-specificreference signals that are indicated by the base station device.

FIG. 9 is a diagram that illustrates an example of a flow according tothis embodiment. As illustrated in FIG. 9, the base station deviceswitches, based on a condition, between the transmission on the PDSCHbased on the PCI and the transmission on the PDSCH based on the firstconfiguration. Further, the terminal device switches between thereception on the PDSCH based on the PCI and the reception on the PDSCHbased on the first configuration.

That is, in a case of a condition A, the base station device performsthe rate-matching based only on the positions of the cell-specificreference signals that are determined in accordance with the physicallayer cell identity of the serving cell and performs transmission on thePDSCH.

That is, for example, in the case of the condition A, the base stationdevice maps the PDSCH to the resource elements in the physical resourceblocks that are allocated for transmission on the PDSCH. Further, in thecase of the condition A, the base station device maps the PDSCH to theresource elements that are not used for transmission of thecell-specific reference signals.

Further, in a case of a condition B, the base station device performsthe rate-matching based on the positions of the cell-specific referencesignals that are indicated for the terminal device and performstransmission on the PDSCH.

That is, for example, in the case of the condition B, the base stationdevice maps the PDSCH to the resource elements in the physical resourceblocks that are allocated for transmission on the PDSCH except theresource elements that are indicated for the terminal device. Further,in the case of the condition B, the base station device maps the PDSCHto the resource elements that are not used for transmission of thecell-specific reference signal.

Further, in the case of the condition A, the terminal device performsreception on the PDSCH while assuming that the rate-matching isperformed based only on the positions of the cell-specific referencesignals that are determined in accordance with the physical layer cellidentity of the serving cell.

That is, in the case of the condition A, the terminal device receivesthe PDSCH that is mapped to the resource elements in the physicalresource blocks that are allocated for transmission on the PDSCH.Further, in the case of the condition A, the terminal device receivesthe PDSCH that is mapped to the resource elements that are not used fortransmission of the cell-specific reference signals.

Further, in the case of the condition B, the terminal device receivesthe PDSCH while assuming that the rate-matching is performed based onthe positions of the cell-specific reference signals that are indicatedby the base station device.

That is, in the case of the condition B, the terminal device receivesthe PDSCH that is mapped to the resource element in the physicalresource blocks that are allocated for transmission on the PDSCH exceptthe resource elements that are indicated (specified or configured) bythe base station device. That is, in the case of the condition B, theterminal device receives the PDSCH that is mapped to the resourceelements that are not used for transmission of the cell-specificreference signal.

Here, the condition A includes transmission (allocation) of the PDCCH inthe CSS. Further, the condition A includes detection (decoding orreception) of the PDCCH in the CSS.

That is, in a case where the PDCCH is transmitted (that may beallocated) in the CSS, the base station device performs the transmissionon the PDSCH based on the PCI. Further, in a case where the PDCCH isdetected in the CSS, the terminal device performs the reception on thePDSCH based on the PCI.

Further, the condition B includes transmission (allocation) of the PDCCHin the USS. Further, the condition B includes detection (decoding orreception) of the PDCCH in the USS.

That is, in a case where the PDCCH is transmitted in the USS, the basestation device performs the transmission on the PDSCH based on the firstconfiguration. Further, in a case where the PDCCH is detected in theUSS, the terminal device performs the reception on the PDSCH based onthe first condition.

Further, the condition A includes transmission of a predetermined DCIformat (hereinafter denoted as a first DCI format also). Further, thecondition A includes detection (decoding or reception) of thepredetermined DCI format. Here, the first DCI format is defined inadvance by a specification or the like and may be provided as knowninformation between the base station device and the terminal device.

Here, for example, the first DCI format represents the DCI format 1A.Further, a new DCI format may be defined as the first DCI format. Here,the DCI format 1A may be transmitted on the PDCCH in the CSS and/or theUSS.

That is, in a case where the first DCI format (for example, the DCIformat 1A) is transmitted, the base station device performs thetransmission on the PDSCH based on the PCI. Further, in a case where thefirst DCI format (for example, the DCI format 1A) is received, theterminal device performs the reception on the PDSCH based on the PCI.

Further, the condition B includes transmission of a DCI format otherthan the predetermined DCI format (hereinafter denoted as a second DCIformat or a DCI format that is different from the predetermined DCIformat also). Further, the condition B includes detection (decoding orreception) of the DCI format other than the predetermined DCI format.

Here, for example, the second DCI format represents a DCI format otherthan the DCI format 1A. For example, the second DCI format includes theDCI format 2 (that may be the DCI format 2C). Further, the second DCIformat includes the DCI format X. Further, a new DCI format may bedefined as the second DCI format.

That is, in a case where the second DCI format (for example, a DCIformat other than the DCI format 1A) is transmitted, the base stationdevice performs the transmission on the PDSCH based on the firstconfiguration. Further, in a case where the second DCI format (forexample, a DCI format other than the DCI format 1A) is received, theterminal device performs the reception on the PDSCH based on the firstconfiguration.

Further, the condition A includes transmission (allocation) of the firstDCI format in the CSS. Further, the condition A includes detection(decoding or reception) of the first DCI format in the CSS. That is, forexample, the condition A includes transmission of the DCI format 1A inthe CSS. Further, the condition A includes reception of the DCI format1A in the CSS.

That is, in a case where the first DCI format (for example, the DCIformat 1A) is transmitted in the CSS, the base station device performsthe transmission on the PDSCH based on the PCI. Further, in a case wherethe first DCI format (for example, the DCI format 1A) is received in theCSS, the terminal device performs the reception on the PDSCH based onthe PCI.

Further, the condition B includes transmission of the first DCI formator the second DCI format in the USS. Further, the condition B includestransmission of the second DCI format in the CSS. Further, the conditionB includes detection (decoding or reception) of the first DCI format orthe second DCI format in the USS. Further, the condition B includesdetection (decoding or reception) of the second DCI format in the CSS.

That is, in a case where the first DCI format (for example, the DCIformat 1A) or the second DCI format (for example, a DCI format otherthan the DCI format 1A) is transmitted in the USS, the base stationdevice performs the transmission on the PDSCH based on the firstconfiguration. Further, in a case where the second DCI format (forexample, a DCI format other than the DCI format 1A) is transmitted inthe CSS, the base station device performs the transmission on the PDSCHbased on the first configuration.

Further, in a case where the first DCI format (for example, the DCIformat 1A) or the second DCI format (for example, a DCI format otherthan the DCI format 1A) is received in the USS, the terminal deviceperforms the reception on the PDSCH based on the first configuration.Further, in a case where the second DCI format (for example, a DCIformat other than the DCI format 1A) is received in the CSS, theterminal device performs the reception on the PDSCH based on the firstconfiguration.

Further, the condition A includes transmission (allocation) of the PDCCHwith the CRC scrambled by the RA-RNTI. Further, the condition A includestransmission of the PDCCH with the CRC scrambled by the P-RNTI. Further,the condition A includes transmission of the PDCCH with the CRCscrambled by the SI-RNTI.

Further, the condition A includes detection (decoding or reception) ofthe PDCCH with the CRC scrambled by the RA-RNTI. Further, the conditionA includes detection of the PDCCH with the CRC scrambled by the P-RNTI.Further, the condition A includes detection of the PDCCH with the CRCscrambled by the SI-RNTI.

That is, in a case where the PDCCH with the CRC scrambled by the RA-RNTIis transmitted, the base station device performs the transmission on thePDSCH based on the PCI. Further, in a case where the PDCCH with the CRCscrambled by the P-RNTI is transmitted, the base station device performsthe transmission on the PDSCH based on the PCI. Further, in a case wherethe PDCCH with the CRC scrambled by the SI-RNTI is transmitted, the basestation device performs the transmission on the PDSCH based on the PCI.

Further, in a case where the PDCCH with the CRC scrambled by the RA-RNTIis detected, the terminal device performs the reception on the PDSCHbased on the PCI. Further, in a case where the PDCCH with the CRCscrambled by the P-RNTI is detected, the terminal device performs thereception on the PDSCH based on the PCI. Further, in a case where thePDCCH with the CRC scrambled by the SI-RNTI is detected, the terminaldevice performs the reception on the PDSCH based on the PCI.

Further, the condition B includes transmission (allocation) of the PDCCHwith the CRC scrambled by the C-RNTI. Further, the condition B includesdetection (decoding or reception) of the PDCCH with the CRC scrambled bythe C-RNTI.

That is, in a case where the PDCCH with the CRC scrambled by the C-RNTIis transmitted, the base station device performs the transmission on thePDSCH based on the first configuration. Further, in a case where thePDCCH with the CRC scrambled by the C-RNTI is detected, the terminaldevice performs the reception on the PDSCH based on the firstconfiguration.

FIG. 10 is another diagram that illustrates an example of a flowaccording to this embodiment. Here, as described above, in a certainMBSFN subframe, the cell-specific reference signals are transmitted onlyin the non-MBSFN area in the MBSFN subframe.

That is, for example, in a case where the cell 1 corresponds to thenon-MBSFN subframe, the cell 2 corresponds to the MBSFN subframe, and acell 3 corresponds to the non-MBSFN subframe in certain subframes, thebase station device and the terminal device may perform transmission andreception on the PDSCH based on the positions of the cell-specificreference signals that correspond to the cell 1 and the positions of thecell-specific reference signals that correspond to the cell 3.

That is, for example, based on whether a certain subframe in a certaincell is the MBSFN subframe or the non-MBSFN subframe, the base stationdevice and the terminal device may switch between performingtransmission and reception on the PDSCH based on the positions of thecell-specific reference signals that correspond to the cell and notperforming that.

In FIG. 10, the base station device switches operations (processes) inaccordance with the condition. Here, the conditions (the condition A andthe condition B) are as described above. Here, in the case of thecondition A, the base station device identifies (recognizes or confirms)whether the subframe in the serving cell is the MBSFN subframe or thenon-MBSFN subframe.

Here, in a case of the MBSFN subframe in the serving cell, the basestation device does not perform the rate-matching based on the positionsof the cell-specific reference signals of the serving cell and performstransmission on the PDSCH. That is, the base station device does notperform the rate-matching based on the positions of the cell-specificreference signals that are determined in accordance with the physicallayer cell identity of the serving cell and performs transmission on thePDSCH.

Further, in a case of the non-MBSFN subframe in the serving cell, thebase station device performs the rate-matching based only on thepositions of the cell-specific reference signals of the serving cell andperforms transmission on the PDSCH. That is, the base station deviceperforms the transmission on the PDSCH based on the PCI.

Further, in the case of the condition B, the base station deviceidentifies (recognizes or confirms) whether the subframe in a patternthat is configured for the terminal device (that is, a pattern of theMBSFN subframe) is the MBSFN subframe or the non-MB SFN subframe. Asdescribed above, the base station device may configure the MBSFNsubframe (the pattern of the MBSFN subframe) by transmitting parameters(for example, the information about the MBSFN subframe) by using thehigher layer signaling.

Here, in a case of the MBSFN subframe in the configured pattern, thebase station device does not perform the rate-matching based on theindicated positions of the cell-specific reference signals and performstransmission on the PDSCH. That is, the base station device does notperform the rate-matching based on the positions of the cell-specificreference signals that are indicated by using the user-equipmentspecific configuration and performs transmission on the PDSCH.

Further, in a case of the non-MBSFN subframe in the configured pattern,the base station device performs the rate-matching based on theindicated positions of the cell-specific reference signals and performstransmission on the PDSCH. That is, the base station device performs thetransmission on the PDSCH based on the first configuration.

Similarly, the terminal device switches operations (processes) inaccordance with the condition. Here, the conditions (the condition A andthe condition B) are as described above. Here, in the case of thecondition A, the terminal device identifies (recognizes or confirms)whether the subframe in the serving cell is the MBSFN subframe or thenon-MBSFN subframe.

Here, in the case of the MBSFN subframe in the serving cell, theterminal device performs reception on the PDSCH while assuming that therate-matching based on the positions of the cell-specific referencesignals of the serving cell is not performed. That is, the terminaldevice performs reception on the PDSCH while assuming that therate-matching based on the positions of the cell-specific referencesignals that are determined in accordance with the physical layer cellidentity of the serving cell is not performed.

Further, in the case of the non-MB SFN subframe in the serving cell, theterminal device performs reception on the PDSCH while assuming that therate-matching based only on the positions of the cell-specific referencesignals of the serving cell is performed. That is, the terminal deviceperforms the reception on the PDSCH based on the PCI.

Further, in the case of the condition B, the terminal device identifies(recognizes or confirms) whether the subframe in a pattern that isconfigured by the base station device (that is, the pattern of the MBSFNsubframe) is the MBSFN subframe or the non-MBSFN subframe.

Here, in the case of the MBSFN subframe in the configured pattern, theterminal device performs reception on the PDSCH while assuming that therate-matching based on the indicated positions of the cell-specificreference signals is not performed. That is, the terminal deviceperforms reception on the PDSCH while assuming that the rate-matchingbased on the positions of the cell-specific reference signals that areindicated by using the user-equipment specific configuration is notperformed.

Further, in the case of the non-MB SFN subframe in the configuredpattern, the terminal device performs reception on the PDSCH whileassuming that the rate-matching based on the indicated positions of thecell-specific reference signals is performed. That is, the terminaldevice performs the reception on the PDSCH based on the firstconfiguration.

Here, a case where the resource elements are not the resource elementsthat are indicated (specified or configured) by using information thatis transmitted by the base station device (that may be information thatindicates the positions of the cell-specific reference signals orinformation that indicates the resource elements to which the physicalsignals or physical channels are mapped) will also be denoted as a firstcondition (that may be a first criterion).

Further, a case where the resource elements are present in the physicalresource blocks that are allocated for transmission on the PDSCH willalso be denoted as a second condition (that may be a second criterion).Further, the second condition includes a case where the resourceelements are not used for transmission of the cell-specific referencesignals.

Here, in the above description, a description is basically made about aprocess that is associated with the transmission and reception on thePDSCH based on the positions of the cell-specific reference signals.However, the base station device and the terminal device also performtransmission and reception on the PDSCH based on the resource elementsto which the physical signals or physical channels other than thecell-specific reference signals are mapped.

Here, for example, the physical signals other than the cell-specificreference signal include the user equipment-specific reference signals,the MBSFN reference signals, channel state information referencesignals, the synchronization signals, and so forth. Further, thephysical channels other the cell-specific reference signal include aphysical broadcast channel (PBCH).

Further, for example, the base station device and the terminal devicetransmit and receive the PDSCH that is mapped to the resource elementsexcept the resource elements of the OFDM symbols that satisfyI<IDataStart in the first slot. Here, I denotes the numbers of the OFDMsymbols in the slot. Further, the base station device may transmitinformation that indicates IDataStart to the terminal device.

Here, a case where the resource elements are not used for transmissionof the physical signals other than the cell-specific reference signalsis included in the second condition. Further, a case where the resourceelements are not used for transmission of the physical channels otherthan the cell-specific reference signal is included in the secondcondition. Further, the second condition includes a case where theresource elements satisfy I<IDataStart in the first slot.

That is, the second condition includes at least a case where theresource elements are present in the physical resource blocks that areallocated for transmission on the PDSCH. Further, the second conditionincludes at least a case where the resource elements are not used fortransmission of the cell-specific reference signals.

As described above, the base station device and the terminal device maytransmit and receive information that indicates (specifies orconfigures) the resource elements. Here, the information that indicatesthe resource elements includes information that indicates the positions(allocations) of the resource elements. Further, the information thatindicates the resource elements includes information that indicates theresource elements in which the neighboring cell (also referred to asother cell, coordinated cell, or associated cell) transmits the physicalsignal or physical channel.

Further, in the case of the condition B, the base station device mapsthe PDSCH to the resource elements that satisfy the first condition andthe second condition. Further, in the case of the condition A, the basestation device maps the PDSCH to the resource elements that satisfy thesecond condition.

Further, in the case of the condition B, the terminal device receivesthe PDSCH that is mapped to the resource elements that satisfy the firstcondition and the second condition. Further, in the case of thecondition A, the terminal device receives the PDSCH that is mapped tothe resource elements that satisfy the second condition.

An above-described method allows the base station device and theterminal device to transmit and receive the PDSCH without degrading thereceive performance and to perform communication that efficiently usesradio resources. Further, the above-described method enablestransmission and reception on the PDSCH while the positions of thephysical signals or physical channels other than the PDSCH is moredynamically taken into account and thereby enables communication thatefficiently uses the radio resources.

Further, the base station device and the terminal device may transmitand receive the PDSCH by using the condition A in a period in which aconfiguration in the RRC layer is performed (for example, a period inwhich a configuration by using the dedicated signals is performed). Thatis, transmission and reception on the PDSCH may be performed by usingthe condition A in a period which is caused while the configuration inthe RRC layer is performed and in which the configuration is uncertain(unclear) (a period in which disagreement in the configuration occursbetween the base station device and the terminal device).

That is, the base station device and the terminal device may maintaincommunication even in a period in which the configuration in the RRClayer is performed and may thereby perform communication thatefficiently uses radio resources.

As described above, the base station device in this embodiment is a basestation device that transmits the physical downlink shared channel tothe mobile station device and includes transmitting information thatindicates the resource element to the mobile station device,transmitting the physical downlink control channel that is used forscheduling the physical downlink shared channel to the mobile stationdevice in the common search space or the user equipment-specific searchspace, mapping the physical downlink shared channel to the resourceelement that satisfies the first condition and the second condition in acase where the physical downlink control channel is transmitted in theuser equipment-specific search space, and mapping the physical downlinkshared channel to the resource element that satisfies the secondcondition in a case where the physical downlink control channel istransmitted in the common search space. The first condition is that theresource element is not the resource element that is indicated by usingthe information by the base station device, and the second condition isthat the resource element is at least in the physical resource blockthat is allocated for transmission of the physical downlink sharedchannel.

Further, the base station device in this embodiment is a base stationdevice that transmits the physical downlink shared channel to the mobilestation device and includes transmitting information that indicates theresource element to the mobile station device, mapping the physicaldownlink shared channel to the resource element that satisfies the firstcondition and the second condition in a case where a prescribed downlinkcontrol information format that is used for scheduling the physicaldownlink shared channel is transmitted, and mapping the physicaldownlink shared channel to the resource element that satisfies thesecond condition in a case where the downlink control information formatthat is different from the prescribed downlink control informationformat that is used for scheduling the physical downlink shared channelis transmitted. The first condition is that the resource element is notthe resource element that is indicated by using the information by thebase station device, and the second condition is that the resourceelement is at least in the physical resource block that is allocated fortransmission of the physical downlink shared channel.

Further, the base station device in this embodiment is a base stationdevice that transmits the physical downlink shared channel to the mobilestation device and includes transmitting information that indicates theresource element to the mobile station device, mapping the physicaldownlink shared channel to the resource element that satisfies the firstcondition and the second condition in a case where a prescribed downlinkcontrol information format that is used for scheduling the physicaldownlink shared channel or the downlink control information format thatis different from the prescribed downlink control information format istransmitted in the user equipment-specific search space, and mapping thephysical downlink shared channel to the resource element that satisfiesthe second condition in a case where the prescribed downlink controlinformation format that is used for scheduling the physical downlinkshared channel is transmitted in the common search space. The firstcondition is that the resource element is not the resource element thatis indicated by using the information by the base station device, andthe second condition is that the resource element is at least in thephysical resource block that is allocated for transmission of thephysical downlink shared channel.

Further, the mobile station device in this embodiment is a mobilestation device that receives the physical downlink shared channel fromthe base station device and includes receiving information thatindicates the resource element from the base station device, monitoringthe physical downlink control channel that is used for scheduling thephysical downlink shared channel in the common search space and/or theuser equipment-specific search space, receiving the physical downlinkshared channel that is mapped to the resource element that satisfies thefirst condition and the second condition from the base station device ina case where the physical downlink control channel is detected in theuser equipment-specific search space, and receiving the physicaldownlink shared channel that is mapped to the resource element thatsatisfies the second condition from the base station device in a casewhere the physical downlink control channel is detected in the commonsearch space. The first condition is that the resource element is notthe resource element that is indicated by using the information by thebase station device, and the second condition is that the resourceelement is at least in the physical resource block that is allocated fortransmission of the physical downlink shared channel.

Further, the mobile station device in this embodiment is a mobilestation device that receives the physical downlink shared channel fromthe base station device and includes receiving information thatindicates the resource element from the base station device, receivingthe physical downlink shared channel that is mapped to the resourceelement that satisfies the first condition and the second condition fromthe base station device in a case where a prescribed downlink controlinformation format that is used for scheduling the physical downlinkshared channel is received, and receiving the physical downlink sharedchannel that is mapped to the resource element that satisfies the secondcondition from the base station device in a case where the downlinkcontrol information format that is different from the prescribeddownlink control information format that is used for scheduling thephysical downlink shared channel is received. The first condition isthat the resource element is not the resource element that is indicatedby using the information by the base station device, and the secondcondition is that the resource element is at least in the physicalresource block that is allocated for transmission of the physicaldownlink shared channel.

Further, the mobile station device in this embodiment is a mobilestation device that receives the physical downlink shared channel fromthe base station device and includes receiving information thatindicates the resource element from the base station device, receivingthe physical downlink shared channel that is mapped to the resourceelement that satisfies the first condition and the second condition fromthe base station device in a case where a prescribed downlink controlinformation format that is used for scheduling the physical downlinkshared channel or the downlink control information format that isdifferent from the prescribed downlink control information format isreceived in the user equipment-specific search space, and receiving thephysical downlink shared channel that is mapped to the resource elementthat satisfies the second condition from the base station device in acase where the prescribed downlink control information format that isused for scheduling the physical downlink shared channel is received inthe common search space. The first condition is that the resourceelement is not the resource element that is indicated by using theinformation by the base station device, and the second condition is thatthe resource element is at least in the physical resource block that isallocated for transmission of the physical downlink shared channel.

Further, a transmission method in this embodiment is a transmissionmethod of a base station device that transmits the physical downlinkshared channel to the mobile station device and includes transmittinginformation that indicates the resource element to the mobile stationdevice, transmitting the physical downlink control channel that is usedfor scheduling the physical downlink shared channel to the mobilestation device in the common search space or the user equipment-specificsearch space, mapping the physical downlink shared channel to theresource element that satisfies the first condition and the secondcondition in a case where the physical downlink control channel istransmitted in the user equipment-specific search space, and mapping thephysical downlink shared channel to the resource element that satisfiesthe second condition in a case where the physical downlink controlchannel is transmitted in the common search space. The first conditionis that the resource element is not the resource element that isindicated by using the information by the base station device, and thesecond condition is that the resource element is at least in thephysical resource block that is allocated for transmission of thephysical downlink shared channel.

Further, a transmission method in this embodiment is a transmissionmethod of a base station device that transmits the physical downlinkshared channel to the mobile station device and includes transmittinginformation that indicates the resource element to the mobile stationdevice, mapping the physical downlink shared channel to the resourceelement that satisfies the first condition and the second condition in acase where a prescribed downlink control information format that is usedfor scheduling the physical downlink shared channel is transmitted, andmapping the physical downlink shared channel to the resource elementthat satisfies the second condition in a case where the downlink controlinformation format that is different from the prescribed downlinkcontrol information format that is used for scheduling the physicaldownlink shared channel is transmitted. The first condition is that theresource element is not the resource element that is indicated by usingthe information by the base station device, and the second condition isthat the resource element is at least in the physical resource blockthat is allocated for transmission of the physical downlink sharedchannel.

Further, a transmission method in this embodiment is a transmissionmethod of a base station device that transmits the physical downlinkshared channel to the mobile station device and includes transmittinginformation that indicates the resource element to the mobile stationdevice, mapping the physical downlink shared channel to the resourceelement that satisfies the first condition and the second condition in acase where a prescribed downlink control information format that is usedfor scheduling the physical downlink shared channel or the downlinkcontrol information format that is different from the prescribeddownlink control information format is transmitted in the userequipment-specific search space, and mapping the physical downlinkshared channel to the resource element that satisfies the secondcondition in a case where the prescribed downlink control informationformat that is used for scheduling the physical downlink shared channelis transmitted in the common search space. The first condition is thatthe resource element is not the resource element that is indicated byusing the information by the base station device, and the secondcondition is that the resource element is at least in the physicalresource block that is allocated for transmission of the physicaldownlink shared channel.

Further, a transmission method in this embodiment is a transmissionmethod of a mobile station device that receives the physical downlinkshared channel from the base station device and includes receivinginformation that indicates the resource element from the base stationdevice, monitoring the physical downlink control channel that is usedfor scheduling the physical downlink shared channel in the common searchspace and/or the user equipment-specific search space, receiving thephysical downlink shared channel that is mapped to the resource elementthat satisfies the first condition and the second condition from thebase station device in a case where the physical downlink controlchannel is detected in the user equipment-specific search space, andreceiving the physical downlink shared channel that is mapped to theresource element that satisfies the second condition from the basestation device in a case where the physical downlink control channel isdetected in the common search space. The first condition is that theresource element is not the resource element that is indicated by usingthe information by the base station device, and the second condition isthat the resource element is at least in the physical resource blockthat is allocated for transmission of the physical downlink sharedchannel.

Further, a transmission method in this embodiment is a transmissionmethod of a mobile station device that receives the physical downlinkshared channel from the base station device and includes receivinginformation that indicates the resource element from the base stationdevice, receiving the physical downlink shared channel that is mapped tothe resource element that satisfies the first condition and the secondcondition from the base station device in a case where a prescribeddownlink control information format that is used for scheduling thephysical downlink shared channel is received, and receiving the physicaldownlink shared channel that is mapped to the resource element thatsatisfies the second condition from the base station device in a casewhere the downlink control information format that is different from theprescribed downlink control information format that is used forscheduling the physical downlink shared channel is received. The firstcondition is that the resource element is not the resource element thatis indicated by using the information by the base station device, andthe second condition is that the resource element is at least in thephysical resource block that is allocated for transmission of thephysical downlink shared channel.

Further, a transmission method in this embodiment is a transmissionmethod of a mobile station device that receives the physical downlinkshared channel from the base station device and includes receivinginformation that indicates the resource element from the base stationdevice, receiving the physical downlink shared channel that is mapped tothe resource element that satisfies the first condition and the secondcondition from the base station device in a case where a prescribeddownlink control information format that is used for scheduling thephysical downlink shared channel or the downlink control informationformat that is different from the prescribed downlink controlinformation format is received in the user equipment-specific searchspace, and receiving the physical downlink shared channel that is mappedto the resource element that satisfies the second condition from thebase station device in a case where the prescribed downlink controlinformation format that is used for scheduling the physical downlinkshared channel is received in the common search space. The firstcondition is that the resource element is not the resource element thatis indicated by using the information by the base station device, andthe second condition is that the resource element is at least in thephysical resource block that is allocated for transmission of thephysical downlink shared channel.

Further, an integrated circuit in this embodiment is an integratedcircuit that is installed in a base station device that transmits thephysical downlink shared channel to the mobile station device and causesthe base station device to provide a function of transmittinginformation that indicates the resource element to the mobile stationdevice, a function of transmitting the physical downlink control channelthat is used for scheduling the physical downlink shared channel to themobile station device in the common search space or the userequipment-specific search space, a function of mapping the physicaldownlink shared channel to the resource element that satisfies the firstcondition and the second condition in a case where the physical downlinkcontrol channel is transmitted in the user equipment-specific searchspace, and a function of mapping the physical downlink shared channel tothe resource element that satisfies the second condition in a case wherethe physical downlink control channel is transmitted in the commonsearch space. The first condition is that the resource element is notthe resource element that is indicated by using the information by thebase station device, and the second condition is that the resourceelement is at least in the physical resource block that is allocated fortransmission of the physical downlink shared channel.

Further, an integrated circuit in this embodiment is an integratedcircuit that is installed in a base station device that transmits thephysical downlink shared channel to the mobile station device and causesthe base station device to provide a function of transmittinginformation that indicates the resource element to the mobile stationdevice, a function of mapping the physical downlink shared channel tothe resource element that satisfies the first condition and the secondcondition in a case where a prescribed downlink control informationformat that is used for scheduling the physical downlink shared channelis transmitted, and a function of mapping the physical downlink sharedchannel to the resource element that satisfies the second condition in acase where the downlink control information format that is differentfrom the prescribed downlink control information format that is used forscheduling the physical downlink shared channel is transmitted. Thefirst condition is that the resource element is not the resource elementthat is indicated by using the information by the base station device,and the second condition is that the resource element is at least in thephysical resource block that is allocated for transmission of thephysical downlink shared channel.

Further, an integrated circuit in this embodiment is an integratedcircuit that is installed in a base station device that transmits thephysical downlink shared channel to the mobile station device and causesthe base station device to provide a function of transmittinginformation that indicates the resource element to the mobile stationdevice, a function of mapping the physical downlink shared channel tothe resource element that satisfies the first condition and the secondcondition in a case where a prescribed downlink control informationformat that is used for scheduling the physical downlink shared channelor the downlink control information format that is different from theprescribed downlink control information format is transmitted in theuser equipment-specific search space, and a function of mapping thephysical downlink shared channel to the resource element that satisfiesthe second condition in a case where the prescribed downlink controlinformation format that is used for scheduling the physical downlinkshared channel is transmitted in the common search space. The firstcondition is that the resource element is not the resource element thatis indicated by using the information by the base station device, andthe second condition is that the resource element is at least in thephysical resource block that is allocated for transmission of thephysical downlink shared channel.

Further, an integrated circuit in this embodiment is an integratedcircuit that is installed in a mobile station device that receives thephysical downlink shared channel from the base station device and causesthe mobile station device to provide a function of receiving informationthat indicates the resource element from the base station device, afunction of monitoring the physical downlink control channel that isused for scheduling the physical downlink shared channel in the commonsearch space and/or the user equipment-specific search space, a functionof receiving the physical downlink shared channel that is mapped to theresource element that satisfies the first condition and the secondcondition from the base station device in a case where the physicaldownlink control channel is detected in the user equipment-specificsearch space, and a function of receiving the physical downlink sharedchannel that is mapped to the resource element that satisfies the secondcondition from the base station device in a case where the physicaldownlink control channel is detected in the common search space. Thefirst condition is that the resource element is not the resource elementthat is indicated by using the information by the base station device,and the second condition is that the resource element is at least in thephysical resource block that is allocated for transmission of thephysical downlink shared channel.

Further, an integrated circuit in this embodiment is an integratedcircuit that is installed in a mobile station device that receives thephysical downlink shared channel from the base station device and causesthe mobile station device to provide a function of receiving informationthat indicates the resource element from the base station device, afunction of receiving the physical downlink shared channel that ismapped to the resource element that satisfies the first condition andthe second condition from the base station device in a case where aprescribed downlink control information format that is used forscheduling the physical downlink shared channel is received, and afunction of receiving the physical downlink shared channel that ismapped to the resource element that satisfies the second condition fromthe base station device in a case where the downlink control informationformat that is different from the prescribed downlink controlinformation format that is used for scheduling the physical downlinkshared channel is received. The first condition is that the resourceelement is not the resource element that is indicated by using theinformation by the base station device, and the second condition is thatthe resource element is at least in the physical resource block that isallocated for transmission of the physical downlink shared channel.

Further, an integrated circuit in this embodiment is an integratedcircuit that is installed in a mobile station device that receives thephysical downlink shared channel from the base station device and causesthe mobile station device to provide a function of receiving informationthat indicates the resource element from the base station device, afunction of receiving the physical downlink shared channel that ismapped to the resource element that satisfies the first condition andthe second condition from the base station device in a case where aprescribed downlink control information format that is used forscheduling the physical downlink shared channel or the downlink controlinformation format that is different from the prescribed downlinkcontrol information format is received in the user equipment-specificsearch space, and a function of receiving the physical downlink sharedchannel that is mapped to the resource element that satisfies the secondcondition from the base station device in a case where the prescribeddownlink control information format that is used for scheduling thephysical downlink shared channel is received in the common search space.The first condition is that the resource element is not the resourceelement that is indicated by using the information by the base stationdevice, and the second condition is that the resource element is atleast in the physical resource block that is allocated for transmissionof the physical downlink shared channel.

Further, a mobile communication system in this embodiment is a mobilecommunication system in which a mobile station device receives thephysical downlink shared channel from a base station device and in whichthe base station device transmits information that indicates theresource element to the mobile station device and transmits the physicaldownlink control channel that is used for scheduling the physicaldownlink shared channel in the common search space and/or the userequipment-specific search space to the mobile station device, and themobile station device receives the physical downlink shared channel thatis mapped to the resource element that satisfies the first condition andthe second condition from the base station device in a case where thephysical downlink control channel is detected in the userequipment-specific search space and receives the physical downlinkshared channel that is mapped to the resource element that satisfies thesecond condition from the base station device in a case where thephysical downlink control channel is detected in the common searchspace. The first condition is that the resource element is not theresource element that is indicated by using the information by the basestation device, and the second condition is that the resource element isat least in the physical resource block that is allocated fortransmission of the physical downlink shared channel.

Further, a mobile communication system in this embodiment is a mobilecommunication system in which a mobile station device receives thephysical downlink shared channel from the base station device and inwhich the base station device transmits information that indicates theresource element to the mobile station device, and the mobile stationdevice receives the physical downlink shared channel that is mapped tothe resource element that satisfies the first condition and the secondcondition from the base station device in a case where a prescribeddownlink control information format that is used for scheduling thephysical downlink shared channel is received and receives the physicaldownlink shared channel that is mapped to the resource element thatsatisfies the second condition from the base station device in a casewhere the downlink control information format that is different from theprescribed downlink control information format that is used forscheduling the physical downlink shared channel is received. The firstcondition is that the resource element is not the resource element thatis indicated by using the information by the base station device, andthe second condition is that the resource element is at least in thephysical resource block that is allocated for transmission of thephysical downlink shared channel.

Further, a mobile communication system in this embodiment is mobilecommunication system in which a mobile station device receives thephysical downlink shared channel from the base station device and inwhich the base station device transmits information that indicates theresource element to the mobile station device, and the mobile stationdevice receives the physical downlink shared channel that is mapped tothe resource element that satisfies the first condition and the secondcondition from the base station device in a case where a prescribeddownlink control information format that is used for scheduling thephysical downlink shared channel or the downlink control informationformat that is different from the prescribed downlink controlinformation format is received in the user equipment-specific searchspace and receives the physical downlink shared channel that is mappedto the resource element that satisfies the second condition from thebase station device in a case where the prescribed downlink controlinformation format that is used for scheduling the physical downlinkshared channel is received in the common search space. The firstcondition is that the resource element is not the resource element thatis indicated by using the information by the base station device, andthe second condition is that the resource element is at least in thephysical resource block that is allocated for transmission of thephysical downlink shared channel.

A program that operates in the primary base station, the secondary basestation, and the terminal device that relate to the present invention isa program that controls a CPU or the like so that functions of the aboveembodiment related to the present invention are realized (a program thatallows a computer to function). In addition, information that is dealtwith by such devices is temporarily accumulated in a RAM during aprocess of the information, thereafter stored in various kinds of ROMsor HDDs. The information is read out, corrected, and written by the CPUas necessary. Recording media to store the program may be any ofsemiconductor media (for example, ROM, non-volatile memory card, and soforth), optical recording media (for example, DVD, MO, MD, CD, BD, andso forth), magnetic recording media (for example, magnetic tape,flexible disk, and so forth), and so forth. Further, there may be a casewhere functions of the above-described embodiment are not only realizedby executing the loaded program but also functions of the presentinvention are realized by cooperative processing with an operatingsystem, other application programs, or the like based on instructions ofthe program.

Further, in a case where the program is distributed in market, theprogram may be distributed by storing the program in portable recordingmedia and may be transferred to server computers that are connected viaa network such as the Internet. In such a case, memory devices of theserver computers are included in the present invention. Further, a unitor the whole of the primary base station, the secondary base station,and the terminal device in the above-described embodiment may typicallybe realized as an LSI that is an integrated circuit. Here, functionblocks of the secondary base station, the secondary base station, andthe terminal device may individually be formed into chips, or a unit orthe whole of those may be integrated into a chip. Further, a method offorming the integrated circuit is not limited to an LSI, but theintegrated circuit may be realized as a dedicated circuit, a generalpurpose processor, or the like. Further, in a case where a technology offorming an integrated circuit that replaces the LSI emerges as a resultof progress of a semiconductor technology, an integrated circuit by thetechnology may be used.

The embodiment of the present invention has been described withreference to the drawings in the foregoing. However, a specificconfiguration is not limited to the embodiment, and the presentinvention includes design modifications or the like within a scope thatdoes not depart from the gist of the present invention. Variousmodifications are possible in the scope recited in claims in the presentinvention, and embodiments that are obtained by appropriately combiningtechnical means that are disclosed in different embodiments are includedin the technical scope of the present invention. Further, embodimentsinclude configurations in which elements that are described in the aboveembodiments and provide similar effects are mutually substituted.

INDUSTRIAL APPLICABILITY

The present invention is preferable for a terminal device, a basestation device, a communication method, an integrated circuit, and aradio communication system.

DESCRIPTION OF REFERENCE NUMERALS

-   -   100 base station device    -   101 data control unit    -   102 transmit data modulation unit    -   103 radio unit    -   104 scheduling unit    -   105 channel estimation unit    -   106 receive data demodulation unit    -   107 data extraction unit    -   108 higher layer    -   109 antenna    -   200 terminal device    -   201 data control unit    -   202 transmit data modulation unit    -   203 radio unit    -   204 scheduling unit    -   205 channel estimation unit    -   206 receive data demodulation unit    -   207 data extraction unit    -   208 higher layer    -   209 antenna    -   301 primary base station    -   302 secondary base station    -   303 terminal device    -   304, 305 downlink

1. (canceled)
 2. A user equipment comprising: receiving circuitry thatmonitors, in a non-MBSFN (Multicast/Broadcast over Single FrequencyNetwork) subframe, a first physical downlink control channel with CRC(Cyclic Redundancy Check) scrambled by C-RNTI (Cell-Radio NetworkTemporary Identifier) with a first downlink control information formatand a second physical downlink control channel with CRC scrambled by theC-RNTI with a second downlink control information format, the firstdownlink control information format not including downlink controlinformation, the second downlink control information format includingthe downlink control information, the downlink control informationindicating one parameter set from a plurality of parameter setsconfigured by a higher layer signal, each of the plurality of parametersets providing a frequency shift and a number of antenna ports; thereceiving circuitry that decodes, based on a detection of the firstdownlink control information format, a physical downlink shared channelin the non-MBSFN subframe, resource elements to which the physicaldownlink shared channel is mapped being determined based on positions ofcell-specific reference signals that are given by using a physical layercell identity, wherein the first physical downlink control channel ismonitored in a user equipment-specific search space and a common searchspace.
 3. The user equipment according to claim 2, wherein the secondphysical downlink control channel is monitored only in a userequipment-specific search space.
 4. A base station device comprising:transmitting circuitry that transmits, in a non-MBSFN(Multicast/Broadcast over Single Frequency Network) subframe, a firstphysical downlink control channel with CRC (Cyclic Redundancy Check)scrambled by C-RNTI (Cell-Radio Network Temporary Identifier) with afirst downlink control information format and a second physical downlinkcontrol channel with CRC scrambled by the C-RNTI with a second downlinkcontrol information format, the first downlink control informationformat not including downlink control information, the second downlinkcontrol information format including the downlink control information,the downlink control information indicating one parameter set from aplurality of parameter sets configured by a higher layer signal, each ofthe plurality of parameter sets providing a frequency shift and a numberof antenna ports; the transmitting circuitry that transmits, based onthe first downlink control information format, a physical downlinkshared channel in the non-MBSFN subframe, resource elements to which thephysical downlink shared channel is mapped being determined based onpositions of cell-specific reference signals that are given by using aphysical layer cell identity, wherein the first physical downlinkcontrol channel is transmitted in a user equipment-specific search spaceand a common search space.
 5. The base station device according to claim4, wherein the second physical downlink control channel is monitoredonly in a user equipment-specific search space.
 6. A communicationmethod of a user equipment, the communication method comprising:monitoring, in a non-MBSFN (Multicast/Broadcast over Single FrequencyNetwork) subframe, a first physical downlink control channel with CRC(Cyclic Redundancy Check) scrambled by C-RNTI (Cell-Radio NetworkTemporary Identifier) with a first downlink control information formatand a second physical downlink control channel with CRC scrambled by theC-RNTI with a second downlink control information format, the firstdownlink control information format not including downlink controlinformation, the second downlink control information format includingthe downlink control information, the downlink control informationindicating one parameter set from a plurality of parameter setsconfigured by a higher layer signal, each of the plurality of parametersets providing a frequency shift and a number of antenna ports;decoding, based on a detection of the first downlink control informationformat, a physical downlink shared channel in the non-MBSFN subframe,resource elements to which the physical downlink shared channel ismapped being determined based on positions of cell-specific referencesignals that are given by using a physical layer cell identity, whereinthe first physical downlink control channel is monitored in a userequipment-specific search space and a common search space.
 7. Thecommunication method according to claim 6, wherein the second physicaldownlink control channel is monitored only in a user equipment-specificsearch space.
 8. A communication method of a base station device, thecommunication method comprising: transmitting, in a non-MBSFN(Multicast/Broadcast over Single Frequency Network) subframe, a firstphysical downlink control channel with CRC (Cyclic Redundancy Check)scrambled by C-RNTI (Cell-Radio Network Temporary Identifier) with afirst downlink control information format and a second physical downlinkcontrol channel with CRC scrambled by the C-RNTI with a second downlinkcontrol information format, the first downlink control informationformat not including downlink control information, the second downlinkcontrol information format including the downlink control information,the downlink control information indicating one parameter set from aplurality of parameter sets configured by a higher layer signal, each ofthe plurality of parameter sets providing a frequency shift and a numberof antenna ports; transmitting, based on the first downlink controlinformation format, a physical downlink shared channel in the non-MBSFNsubframe, resource elements to which the physical downlink sharedchannel is mapped being determined based on positions of cell-specificreference signals that are given by using a physical layer cellidentity, wherein the first physical downlink control channel istransmitted in a user equipment-specific search space and a commonsearch space.
 9. The communication method according to claim 8, whereinthe second physical downlink control channel is monitored only in a userequipment-specific search space.